BCM not communicating with ECM?

2008 CHEVROLET COBALT
148,344 MILES • 2.2L • 4 CYL • 2WD • MANUAL
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AZDANNO04
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Vehicle is known to have electrical issues. Layout around engine bay and also bad grounds. If you can, provide me with the wiring diagrams. Also, while I was in midst of replacing my shifter cables, I stopped to double check the replacement cables and weren’t the correct ones even though stated it fits my vehicle but doesn’t have the shims that you pull back to place on the bracket by transmission. Also, the replacement cables have a metal bracket that aligns with the rubber grommet where the vehicle doesn’t have any metal bracket nor would fit that metal piece anywhere. I was using contact cleaner and cleaning around some of the ground areas and on some of the wiring harnesses. I waited over 40 minutes before connecting everything and went to start the vehicle and wouldn’t start and saw the Anti-Theft symbol on the dash. A tech ran an diagnostic and said BCM wasn’t communicating with the ECM but don’t want to get a remanufactured BCM and still won’t start. Got to be a short and or a ground as well. Since prior to the anti-theft. I noticed my vehicle was no crank no start till my cousin had a CAN scan and when we were checking the wiring with the hood up he moved a bundle and that's when we heard a clicking sound. Narrowed it down to a wiring harness that lead to the starter I believe. But I couldn’t find a replacement harness. I carefully removed the wiring harnesses and straightened the wires and placed back in the plug three wires yellow, green, purple.
Feb 19, 2025 at 12:43 PM
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AZDANNO04
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Replacing a Body Control Module. I was able to find one only remanufactured. Provided the VIN number and got the part number from Dorman. Stated No Flash required. Plug and Play. Just needed the steps for replacement.
Feb 19, 2025 at 2:14 PM (Merged)
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STRAILER
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Sure, here is the location of the BCM and how to replace it. Check out the images (below). Let us know if you need anything else.
Feb 20, 2025 at 10:24 AM
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AZDANNO04
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Is there more information? States to reprogram the new BCM and to refer to the BCM references on the setup.
Feb 21, 2025 at 3:03 AM
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STRAILER
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If you are getting a preprogrammed unit, you can disregard that part.
Feb 21, 2025 at 9:46 AM
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AZDANNO04
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The BCM that I am getting just stated no flash required and plug and play, but if it has no VIN number associated with it, it must have some uploading or learning to do.
Feb 21, 2025 at 2:04 PM
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STRAILER
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You are correct unless the BCM self learns which I have not heard of but is possible. Even BCM I have replaced needed programming unless preprogrammed with the VIN.
Feb 22, 2025 at 11:39 AM
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AZDANNO04
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Would jumping the vehicle help?
Feb 22, 2025 at 7:52 PM
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STRAILER
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I don't think so, do you have any CAN codes? You can get a CAN scanner (Controller Area Network) which will work on most cars from Amazon.

Here is a video to show you how:

https://youtu.be/u-4syLc-ifQ

Please go over this guide and get back to us.
Feb 23, 2025 at 10:10 AM